Pentax WG-3 GPS Review

Image Quality

Even though that Pentax WG-3 features the same type of image sensor as its predecessor, we find that its image quality has been enhanced thanks to the new, brighter lens.

Sharpness

Our primary complaint about the WG-2 was that at a distance, landscape photos from it would lack both sharpness and detail.  Everything simply looked like it was smudged, and the poor lens was likely to blame for this.  Let's take a look at how the WG-3 performs with distant subjects.  Here's the test scene (click on either thumbnail to enlarge):

Scene at 4.5mm (widest)	Scene at 18mm (4x zoom, longest)

Here's a 100% crop of the scene at 4.5mm:

Even though the sharpness is not exceptional, this is much better than what the WG-2 could deliver.

At 18mm, the result is also more than acceptable, and so we conclude that the WG-3 improves significantly on the image quality of its predecessor.  Noise reduction is apparent in both crops, but in prints or internet-sized photos from the WG-3 will look just fine.

Detail

In this section, we will look at how increasing the sensor's sensitivity affects image detail. With the WG-3, you can not only control the auto ISO range, but also dial in an ISO manually (using the lowest setting of ISO 125 will obviously result in the clearest photographs, though they will be susceptible to camera shake).

As it is impossible to control the WG-3's program line, a different aperture setting ended up being used for the ISO 800 photo and above in these test photos.  Therefore, the first three and the last four samples should not be compared directly, though they do offer a decent starting point.

ISO 125
ISO 200
ISO 400
ISO 800
ISO 1600
ISO 3200
ISO 6400

What these results show us is that the WG-3 starts to quickly lose detail at higher ISOs, as the camera applies a strong noise reduction algorithm to all its photos.  There is even a clear different between ISO 125 and ISO 200.  We therefore recommend to lock the camera in at ISO 125 if possible.

Even at ISO 125, the WG-3's dynamic range (range of color intensities from darkest to lightest) is very narrow; it is oftentimes difficult to avoid overexposing the sky in landscape photos.  Refer to the same photo section for examples of this.

Distortion

Geometric distortion is present when lines that are straight in real life appear bent inwards (pincushion distortion) or bent outwards (barrel distortion) on a photograph.  The WG-3 does a good job of correcting distortions on its own.  Based on its good performance, we believe that the camera automatically performs distortion correction on all photos.  Using a brick wall test, we found negligible pincushion distortion at 4.5mm and 9mm, and negligible barrel distortion at 18mm.  In Photoshop, the necessary lens correction adjustments were -1.5, -0.5 and +0.5, respectively.

Thus, overall, distortion is a non-issue with the WG-3, except when shooting in macro mode, in which case the corners are subject to extreme distortion:

Click on the photo above to enlarge.

Dark Corners

Dark corners, also known as vignetting, can be observed with most cameras and lenses.  Like distortion, vignetting is fortunately not a big issue on the WG-3.  At the widest setting, the corners are only 5% darker than the center of the frame.  At 9mm, they are 10% darker, and at 18mm, they are 12% darker.  In real life, this difference is hardly discernible.

Aberrations

Aberrations are optical artifacts that are found in an image but not in real life, such as lens flare, halos, or purple fringing. The WG-3 is prone to fringing and detail loss in the corners of the frame, but it is otherwise very good at handling lens flare and other types of aberrations.  This fringing is however pronounced enough that it can make its way into scaled versions of your photos.  This is a 100% crop from the crner of a frame:

Image Quality Enhancer

The WG-3 has a setting called "IQ Enhancer" in its record menu.  Curious about what it did, we decided to take a few sample photos with and without the IQ Enhancer.

Enhanced:

Standard:

At first sight, it looks like the camera improved the contrast, made the colors more vibrant, and cropped away the corners (which could be dark or distorted).  But things change when we examine the 100% crops of each photo.

Enhanced crop:

Standard crop:

It is extremely evident that another round of noise reduction has been applied to the "enhanced" image; this blows away a lot of fine detail and makes an ISO 125 image look like it was taken at a much higher sensitivity.  In other words, for the best pictures, be sure to disable the "IQ Enhancer" and instead use desktop-based or online one-click image correction tools.

Macro and Bokeh

In its macro mode, the WG-3 is capable of producing very smooth backgrounds (also known as bokeh).  The closer you get to your subject, however, the more distorted the corners will appear.  This sample photo is a fairly good example of the kinds of close-ups you can expect from the WG-3.

You can expect the WG-3's macro mode to deliver excellent sharpness in the center:

Image Quality Verdict

The WG-3 delivers good image quality for a point-and-shoot.  Even though the ISO is the only exposure parameter than can be controlled manually, being able to lock the ISO in at its lowest setting will ensure that your camera delivers the clearest images possible.  The fact that the WG-3 has built-in Shake Reduction will undoubtedly improve your "keeper rate" at this low ISO setting.

While the WG-3 still suffers from poor detail at high sensitivities, and sometimes produces excessive purple fringing, we consider its lens to be a very big improvement over that of its predecessor.  Its main weakness is its low dynamic range, which means that highlights can very easily get overexposed.